FR 2 695 285 describes an induction lighting system for domestic use comprising two parts: a first part, corresponding to a wall (or ceiling) fitting, connected to a primary power supply such as the electricity mains; and a second part, corresponding to a luminaire with a light bulb. In the wall fitting, the mains supply is connected to a primary coil. The luminaire has a secondary coil that, in use, is placed next to the primary coil such that power is transferred to the light bulb by induction.
As this system does not require exposed electrical connections on either the wall fitting or the luminaire, safety is improved thereby making it better suited for providing light in a kitchen or bathroom, where extra certification requirements must be met in view of humidity.
However, should the mains supply fail, the light bulb also fails to operate. WO 03/081745 provides an improved induction lighting system, which also includes inductively-powered light modules, each of which comprises both a coil for receiving power from the mains supply and a back-up battery in case the mains supply fails. When a power output from the mains supply is available, the back-up battery may be charged.
However, this document does not address a standard consideration in domestic environments, namely that light switches are provided to switch the light source on and off. With this arrangement, somebody wishing to turn the light off would turn the switch off. This would cause disconnection from the mains supply, which will disable the inductive power supply. This is potentially advantageous, as this change is effected through the light fitting and without exposed electrical connections. However, contrary to requirement, the light will remain switched on, because disconnection of the inductive power supply will enable the alternative power output from the back-up battery in the light module.